1 files changed, 342 insertions, 0 deletions
diff --git a/net/mctp/neigh.c b/net/mctp/neigh.c
new file mode 100644
index 000000000000..90ed2f02d1fb
--- /dev/null
+++ b/net/mctp/neigh.c
@@ -0,0 +1,342 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Management Component Transport Protocol (MCTP) - routing
+ * implementation.
+ *
+ * This is currently based on a simple routing table, with no dst cache. The
+ * number of routes should stay fairly small, so the lookup cost is small.
+ *
+ * Copyright (c) 2021 Code Construct
+ * Copyright (c) 2021 Google
+ */
+
+#include <linux/idr.h>
+#include <linux/mctp.h>
+#include <linux/netdevice.h>
+#include <linux/rtnetlink.h>
+#include <linux/skbuff.h>
+
+#include <net/mctp.h>
+#include <net/mctpdevice.h>
+#include <net/netlink.h>
+#include <net/sock.h>
+
+static int mctp_neigh_add(struct mctp_dev *mdev, mctp_eid_t eid,
+			  enum mctp_neigh_source source,
+			  size_t lladdr_len, const void *lladdr)
+{
+	struct net *net = dev_net(mdev->dev);
+	struct mctp_neigh *neigh;
+	int rc;
+
+	mutex_lock(&net->mctp.neigh_lock);
+	if (mctp_neigh_lookup(mdev, eid, NULL) == 0) {
+		rc = -EEXIST;
+		goto out;
+	}
+
+	if (lladdr_len > sizeof(neigh->ha)) {
+		rc = -EINVAL;
+		goto out;
+	}
+
+	neigh = kzalloc(sizeof(*neigh), GFP_KERNEL);
+	if (!neigh) {
+		rc = -ENOMEM;
+		goto out;
+	}
+	INIT_LIST_HEAD(&neigh->list);
+	neigh->dev = mdev;
+	dev_hold(neigh->dev->dev);
+	neigh->eid = eid;
+	neigh->source = source;
+	memcpy(neigh->ha, lladdr, lladdr_len);
+
+	list_add_rcu(&neigh->list, &net->mctp.neighbours);
+	rc = 0;
+out:
+	mutex_unlock(&net->mctp.neigh_lock);
+	return rc;
+}
+
+static void __mctp_neigh_free(struct rcu_head *rcu)
+{
+	struct mctp_neigh *neigh = container_of(rcu, struct mctp_neigh, rcu);
+
+	dev_put(neigh->dev->dev);
+	kfree(neigh);
+}
+
+/* Removes all neighbour entries referring to a device */
+void mctp_neigh_remove_dev(struct mctp_dev *mdev)
+{
+	struct net *net = dev_net(mdev->dev);
+	struct mctp_neigh *neigh, *tmp;
+
+	mutex_lock(&net->mctp.neigh_lock);
+	list_for_each_entry_safe(neigh, tmp, &net->mctp.neighbours, list) {
+		if (neigh->dev == mdev) {
+			list_del_rcu(&neigh->list);
+			/* TODO: immediate RTM_DELNEIGH */
+			call_rcu(&neigh->rcu, __mctp_neigh_free);
+		}
+	}
+
+	mutex_unlock(&net->mctp.neigh_lock);
+}
+
+// TODO: add a "source" flag so netlink can only delete static neighbours?
+static int mctp_neigh_remove(struct mctp_dev *mdev, mctp_eid_t eid)
+{
+	struct net *net = dev_net(mdev->dev);
+	struct mctp_neigh *neigh, *tmp;
+	bool dropped = false;
+
+	mutex_lock(&net->mctp.neigh_lock);
+	list_for_each_entry_safe(neigh, tmp, &net->mctp.neighbours, list) {
+		if (neigh->dev == mdev && neigh->eid == eid) {
+			list_del_rcu(&neigh->list);
+			/* TODO: immediate RTM_DELNEIGH */
+			call_rcu(&neigh->rcu, __mctp_neigh_free);
+			dropped = true;
+		}
+	}
+
+	mutex_unlock(&net->mctp.neigh_lock);
+	return dropped ? 0 : -ENOENT;
+}
+
+static const struct nla_policy nd_mctp_policy[NDA_MAX + 1] = {
+	[NDA_DST]		= { .type = NLA_U8 },
+	[NDA_LLADDR]		= { .type = NLA_BINARY, .len = MAX_ADDR_LEN },
+};
+
+static int mctp_rtm_newneigh(struct sk_buff *skb, struct nlmsghdr *nlh,
+			     struct netlink_ext_ack *extack)
+{
+	struct net *net = sock_net(skb->sk);
+	struct net_device *dev;
+	struct mctp_dev *mdev;
+	struct ndmsg *ndm;
+	struct nlattr *tb[NDA_MAX + 1];
+	int rc;
+	mctp_eid_t eid;
+	void *lladdr;
+	int lladdr_len;
+
+	rc = nlmsg_parse(nlh, sizeof(*ndm), tb, NDA_MAX, nd_mctp_policy,
+			 extack);
+	if (rc < 0) {
+		NL_SET_ERR_MSG(extack, "lladdr too large?");
+		return rc;
+	}
+
+	if (!tb[NDA_DST]) {
+		NL_SET_ERR_MSG(extack, "Neighbour EID must be specified");
+		return -EINVAL;
+	}
+
+	if (!tb[NDA_LLADDR]) {
+		NL_SET_ERR_MSG(extack, "Neighbour lladdr must be specified");
+		return -EINVAL;
+	}
+
+	eid = nla_get_u8(tb[NDA_DST]);
+	if (!mctp_address_ok(eid)) {
+		NL_SET_ERR_MSG(extack, "Invalid neighbour EID");
+		return -EINVAL;
+	}
+
+	lladdr = nla_data(tb[NDA_LLADDR]);
+	lladdr_len = nla_len(tb[NDA_LLADDR]);
+
+	ndm = nlmsg_data(nlh);
+
+	dev = __dev_get_by_index(net, ndm->ndm_ifindex);
+	if (!dev)
+		return -ENODEV;
+
+	mdev = mctp_dev_get_rtnl(dev);
+	if (!mdev)
+		return -ENODEV;
+
+	if (lladdr_len != dev->addr_len) {
+		NL_SET_ERR_MSG(extack, "Wrong lladdr length");
+		return -EINVAL;
+	}
+
+	return mctp_neigh_add(mdev, eid, MCTP_NEIGH_STATIC,
+			lladdr_len, lladdr);
+}
+
+static int mctp_rtm_delneigh(struct sk_buff *skb, struct nlmsghdr *nlh,
+			     struct netlink_ext_ack *extack)
+{
+	struct net *net = sock_net(skb->sk);
+	struct nlattr *tb[NDA_MAX + 1];
+	struct net_device *dev;
+	struct mctp_dev *mdev;
+	struct ndmsg *ndm;
+	int rc;
+	mctp_eid_t eid;
+
+	rc = nlmsg_parse(nlh, sizeof(*ndm), tb, NDA_MAX, nd_mctp_policy,
+			 extack);
+	if (rc < 0) {
+		NL_SET_ERR_MSG(extack, "incorrect format");
+		return rc;
+	}
+
+	if (!tb[NDA_DST]) {
+		NL_SET_ERR_MSG(extack, "Neighbour EID must be specified");
+		return -EINVAL;
+	}
+	eid = nla_get_u8(tb[NDA_DST]);
+
+	ndm = nlmsg_data(nlh);
+	dev = __dev_get_by_index(net, ndm->ndm_ifindex);
+	if (!dev)
+		return -ENODEV;
+
+	mdev = mctp_dev_get_rtnl(dev);
+	if (!mdev)
+		return -ENODEV;
+
+	return mctp_neigh_remove(mdev, eid);
+}
+
+static int mctp_fill_neigh(struct sk_buff *skb, u32 portid, u32 seq, int event,
+			   unsigned int flags, struct mctp_neigh *neigh)
+{
+	struct net_device *dev = neigh->dev->dev;
+	struct nlmsghdr *nlh;
+	struct ndmsg *hdr;
+
+	nlh = nlmsg_put(skb, portid, seq, event, sizeof(*hdr), flags);
+	if (!nlh)
+		return -EMSGSIZE;
+
+	hdr = nlmsg_data(nlh);
+	hdr->ndm_family = AF_MCTP;
+	hdr->ndm_ifindex = dev->ifindex;
+	hdr->ndm_state = 0; // TODO other state bits?
+	if (neigh->source == MCTP_NEIGH_STATIC)
+		hdr->ndm_state |= NUD_PERMANENT;
+	hdr->ndm_flags = 0;
+	hdr->ndm_type = RTN_UNICAST; // TODO: is loopback RTN_LOCAL?
+
+	if (nla_put_u8(skb, NDA_DST, neigh->eid))
+		goto cancel;
+
+	if (nla_put(skb, NDA_LLADDR, dev->addr_len, neigh->ha))
+		goto cancel;
+
+	nlmsg_end(skb, nlh);
+
+	return 0;
+cancel:
+	nlmsg_cancel(skb, nlh);
+	return -EMSGSIZE;
+}
+
+static int mctp_rtm_getneigh(struct sk_buff *skb, struct netlink_callback *cb)
+{
+	struct net *net = sock_net(skb->sk);
+	int rc, idx, req_ifindex;
+	struct mctp_neigh *neigh;
+	struct ndmsg *ndmsg;
+	struct {
+		int idx;
+	} *cbctx = (void *)cb->ctx;
+
+	ndmsg = nlmsg_data(cb->nlh);
+	req_ifindex = ndmsg->ndm_ifindex;
+
+	idx = 0;
+	rcu_read_lock();
+	list_for_each_entry_rcu(neigh, &net->mctp.neighbours, list) {
+		if (idx < cbctx->idx)
+			goto cont;
+
+		rc = 0;
+		if (req_ifindex == 0 || req_ifindex == neigh->dev->dev->ifindex)
+			rc = mctp_fill_neigh(skb, NETLINK_CB(cb->skb).portid,
+					     cb->nlh->nlmsg_seq,
+					     RTM_NEWNEIGH, NLM_F_MULTI, neigh);
+
+		if (rc)
+			break;
+cont:
+		idx++;
+	}
+	rcu_read_unlock();
+
+	cbctx->idx = idx;
+	return skb->len;
+}
+
+int mctp_neigh_lookup(struct mctp_dev *mdev, mctp_eid_t eid, void *ret_hwaddr)
+{
+	struct net *net = dev_net(mdev->dev);
+	struct mctp_neigh *neigh;
+	int rc = -EHOSTUNREACH; // TODO: or ENOENT?
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(neigh, &net->mctp.neighbours, list) {
+		if (mdev == neigh->dev && eid == neigh->eid) {
+			if (ret_hwaddr)
+				memcpy(ret_hwaddr, neigh->ha,
+				       sizeof(neigh->ha));
+			rc = 0;
+			break;
+		}
+	}
+	rcu_read_unlock();
+	return rc;
+}
+
+/* namespace registration */
+static int __net_init mctp_neigh_net_init(struct net *net)
+{
+	struct netns_mctp *ns = &net->mctp;
+
+	INIT_LIST_HEAD(&ns->neighbours);
+	mutex_init(&ns->neigh_lock);
+	return 0;
+}
+
+static void __net_exit mctp_neigh_net_exit(struct net *net)
+{
+	struct netns_mctp *ns = &net->mctp;
+	struct mctp_neigh *neigh;
+
+	list_for_each_entry(neigh, &ns->neighbours, list)
+		call_rcu(&neigh->rcu, __mctp_neigh_free);
+}
+
+/* net namespace implementation */
+
+static struct pernet_operations mctp_net_ops = {
+	.init = mctp_neigh_net_init,
+	.exit = mctp_neigh_net_exit,
+};
+
+int __init mctp_neigh_init(void)
+{
+	rtnl_register_module(THIS_MODULE, PF_MCTP, RTM_NEWNEIGH,
+			     mctp_rtm_newneigh, NULL, 0);
+	rtnl_register_module(THIS_MODULE, PF_MCTP, RTM_DELNEIGH,
+			     mctp_rtm_delneigh, NULL, 0);
+	rtnl_register_module(THIS_MODULE, PF_MCTP, RTM_GETNEIGH,
+			     NULL, mctp_rtm_getneigh, 0);
+
+	return register_pernet_subsys(&mctp_net_ops);
+}
+
+void __exit mctp_neigh_exit(void)
+{
+	unregister_pernet_subsys(&mctp_net_ops);
+	rtnl_unregister(PF_MCTP, RTM_GETNEIGH);
+	rtnl_unregister(PF_MCTP, RTM_DELNEIGH);
+	rtnl_unregister(PF_MCTP, RTM_NEWNEIGH);
+}